Zika virus Q&A: what we know, what you need to know

Virus now ‘spreading explosively’ in Americas was discovered in Uganda in 1947

Health workers fumigate in an attempt to eradicate the mosquito which transmits the Zika virus on Thursday in Recife, Pernambuco state, Brazil. Zika was first confirmed in Brazil – a country of 200 million – last May, and it spread like wildfire Photograph:  Mario Tama/Getty Images

Health workers fumigate in an attempt to eradicate the mosquito which transmits the Zika virus on Thursday in Recife, Pernambuco state, Brazil. Zika was first confirmed in Brazil – a country of 200 million – last May, and it spread like wildfire Photograph: Mario Tama/Getty Images

 

The World Health Organisation has warned that the Zika virus is “spreading explosively” in the Americas and that as many as four million people could be infected by the end of the year.

The US Centers for Disease Control and Prevention, as well as the European Centre for Disease Surveillance and Control (ECDC), have urged pregnant women against travel to several countries in the Caribbean and Latin America, where the outbreak is growing. The infection appears to be linked to the development of unusually small heads and brain damage in newborns. Here are some answers and advice about the outbreak.

What is the Zika virus?

Brazil

How is the virus spread?

Aedes aegyptiAedes albopictus

How does Zika cause brain damage in infants?

It is not known how common microcephaly has become in Brazil’s outbreak. About three million babies are born in Brazil each year. Normally, about 150 cases of microcephaly are reported, and Brazil says it is investigating nearly 4,000 cases.

What countries should pregnant women avoid?

new travel advice

The HSE has an advice sheet at http://www.hpsc.ie/A-Z/Vectorborne/Zika/.

In the US, the Pan American Health Organization believes that the virus will spread locally in every country in the Americas except Canada and Chile.

Have there been cases of Zika in Europe?

How do I know if I’ve been infected? Is there a test?

There is no widely available test for Zika infection. Because it is closely related to dengue and yellow fever, it may cross-react with antibody tests for those viruses. To detect Zika, a blood or tissue sample from the first week in the infection must be sent to an advanced laboratory so the virus can be detected through sophisticated molecular testing.

I’m pregnant and I recently visited a country with Zika virus. What do I do?

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Does it matter when in her pregnancy a woman is infected with Zika virus?

Is there a treatment?

Is there a vaccine? How should people protect themselves?

According to the European Centre for Disease Surveillance and Control, travellers to affected areas should take individual protective measures to prevent mosquito bites. This include: using mosquito repellents; wearing long-sleeved shirts and long trousers, especially during the hours of highest mosquito activity; and using mosquito nets if accommodation is not adequately screened or air-conditioned.

If the Zika virus has been in Africa and Asia for decades, why wasn’t the microcephaly problem detected earlier?

Until recently, health officials paid little attention to Zika virus. It circulated in the same regions as dengue and chikungunya, and compared to those two painful infections Zika was usually mild. The virus is thought to have reached Asia from Africa at least 50 years ago. While it may have caused spikes in microcephaly as it first spread, there was no testing to pin down which of many possible causes was to blame.

In 2007, a Southeast Asian strain of the Zika virus began leap-frogging the South Pacific, sparking rapid outbreaks on islands where no one had immunity to it. Because island populations are small, rare side effects did not occur often enough to be noticed. But in 2013, during an outbreak in French Polynesia, which has 270,000 residents, doctors confirmed 42 cases of Guillain-Barré syndrome, which can cause paralysis. That was about eight times the normal number and the first hint that Zika virus can attack the nervous system, which includes the brain.

Zika was first confirmed in Brazil – a country of 200 million – last May, and it spread like wildfire. The first alarms about microcephaly were raised only in October, when doctors in the northeastern state of Pernambuco reported a surge in babies born with it. Pernambuco has nine million people and 129,000 annual births. In a typical year, nine are microcephalic infants. By November 2015, when Brazil declared a health emergency, Pernambuco had had 646 such births.

New York Times and additional reporting